package week06;


	import java.util.Arrays;
	import java.util.Scanner;

	interface IntegerStack {
		public Integer push(Integer item);

		public Integer pop();

		public Integer peek();

		public boolean empty();

		public int size();
	}

	class ArrayIntegerStack implements IntegerStack {

		Integer[] stack;
		private int top;

		public ArrayIntegerStack(int n) {
			stack = new Integer[n];
			top = 0;
		}

		public Integer push(Integer item) {
			if (item == null)
				return null;
			if (top == stack.length)
				return null;
			stack[top++] = item;
			return item;

		}

		public Integer pop() {
			if (top == 0)
				return null;
			return stack[--top];
		}

		public Integer peek() {
			if (top == 0)
				return null;
			return stack[top - 1];
		}

		public boolean empty() {
			if (top == 0)
				return true;
			return false;
		}

		public int size() {
			return top;
		}

	}

	public class week0602 {

		public static void main(String[] args) {
			Scanner in = new Scanner(System.in);
			int n = in.nextInt();
			ArrayIntegerStack a = new ArrayIntegerStack(n);
			int m = in.nextInt();
			for (int i = 0; i < m; i++) {
				System.out.println(a.push(in.nextInt()));
			}
			System.out.println(a.peek() + "," + a.empty() + "," + a.size());
			System.out.println(Arrays.toString(a.stack));
			int x = in.nextInt();
			for (int i = 0; i < x; i++) {
				System.out.println(a.pop());
			}
			System.out.println(a.peek() + "," + a.empty() + "," + a.size());
			System.out.println(Arrays.toString(a.stack));
		}

	}


